1. Field of the Invention
This invention relates to methods and apparatus for enhancing water quality. More particularly, it relates to methods and apparatus for providing improved irrigation to vegetation in open areas such as parks and golf courses.
2. Description of the Prior Art
In the past it has commonly been the practice in many cases to manage golf course and park horticulture by what is known as the "sterile field" technique. It is well known that soils contain a wide variety of microorganisms of different types, some of which are beneficial to the plants and grass and others of which are harmful; see Grey et al., eds., The Ecology of Soil Bacteria, (University of Toronto Press: 1968). Since the various mixtures of microorganisms in the different soils are highly complex and vary widely from soil to soil and region to region, it has become common in golf course and park maintenance to apply biocidal materials to sterilize the soil by killing all of the bacteria and other microorganisms, including both harmful and beneficial species. Thereafter, once the biocidal activity has dissipated, the park or golf course manager applies fertilizers, nutrients and beneficial microorganisms to the soil and to some extent maintains an ongoing replenishment of these materials to attempt to keep the soil, grass and other shrubbery of the park or golf course in the desired good condition.
This type of soil management, even though believed generally beneficial, actually causes several problems, some of which are only now beginning to become evident. First, it forces the soil and local vegetation to become dependent upon the application of the chemicals and organisms by the maintenance personnel. In many cases the soil managers do not or cannot know the optimum nutrient and biological requirements of the local soil and vegetation, and therefore the chemical and microorganism materials provided do not supply the optimum nutrition and growth potential to the vegetation.
Further, it has been found that there are a number of soil and vegetation diseases which proliferate only in the sterile soil environment, so much effort must be expended to combat the incursion of these diseases.
There are also many microorganisms in soil which are neither exclusively harmful nor beneficial, but rather play a mixed roll depending on the type of soil and vegetation involved. Thus eliminating all naturally-occurring microorganisms and concentrating solely on the artificial application of "helpful" organisms often leaves the soil and vegetation deprived of the "mixed effect" organisms.
Further, in open areas it is impossible to prevent the re-incorporation into the soil of many of the naturally-occurring organisms which were removed by the sterile field technique initially. Consequently, the golf course or park manager must periodically again sterilize the soil and restart the nutrient supply process.
In addition, in almost all areas of the country incoming water contains dissolved salts, especially sodium salts, which pass through the irrigation system and are deposited onto the soil. The incorporation of such salts into the soil causes the soil to become less porous and receptive to irrigation (more "closed"), and to cause more water to run off and less to be taken up into the soil, such that continuously increasing quantities of irrigation water must be put onto the soil to accomplish satisfactory irrigation of the vegetation. One aspect of this is a particular problem in the arid parts of the United States, such as the West and Southwest, where water is scarce and costly and must be used as efficiently as possible. A converse aspect of the increased need for water to irrigate the closed soils is a particular problem in the wet parts of the United States, such as the South and East, where the excess run-off from poorly utilized irrigation water often poses serious soil erosion problems. In all parts of the country the excess run-off also carries away fertilizes and nutrients which are laid but do not penetrate the soil, resulting in economic waste and loss to the park or golf course owner and pollution of the catch basins and water courses where the run-off ends up.
In park and golf course maintenance, irrigation is a separate operation from fertilizer, nutrient and (where used) microorganism supply. The latter is normally conducted by manual broadcast or deposition on the soil of solid granulated fertilizers or bacterial materials, or such products are dissolved in water to make concentrated solutions or slurries which are manually sprayed onto the soil and vegetation. These operations are labor intensive, time consuming and put course and park workers in prolonged contact with large quantities of chemicals, so that they must be provided with protective clothing and equipment; all of these factors make such maintenance costly. Consequently, in practice it will be found that fertilizers and bacterial materials are only infrequently applied; that the manual applications are usually non-uniform, with numerous areas of the park or course receiving too little or too much material; that resupply of fertilizers and nutrients is performed too infrequently and intermittently to maintain a satisfactory level of viable microorganisms in the soil; and that workers may be at risk of harm when they neglect or refuse to wear and use the protective clothing and equipment furnished to them.
Further, as noted above, such broadcast and deposit methods, and also the spray methods where the soil is at least partially closed, results in fertilizers, nutrients and microorganisms which are merely laid on the surface of the soil. These do not penetrate into the soil and are susceptible to being washed away by irrigation water and rainfall, and in either case do not reach the target vegetation.
The net result of these considerations is that the parks and golf course vegetation does not get the frequent, regular, and optimum nutrition that is needed to produce and maintain healthy, lush and attractive vegetation and to result in a cost effective and economically viable golf course or park operation.
In golf course and park land irrigation, there often may be a relatively large water supply reservoir (such as a pond or lake) from which water is drawn during each day for irrigation and which is replenished as needed, often every night. Over the course of time the content of harmful salts and organisms increases in the water and these materials deposit on the reservoir sides and bottom so that periodically the reservoir much be drained and cleaned, so the water when used will not transfer those harmful organisms and contaminants to the soil or vegetation of the golf courses or parks. In addition, the bottom portion of the water (often extending upward some distance) tends to become depleted in oxygen by various mechanisms. Consequently, this region of oxygen depletion also tends to accumulate anaerobic microorganisms, many of which are harmful to soil and vegetation. Commonly water treatment plants deal with these problems by circulating the water and aerating it. However, in the golf course and park operations, there is usually not sufficient water retention time to provide adequate aeration and water turnover as one finds in commercial water treatment plants. Consequently, when the water is subsequently pumped out of the ponds for the golf course or park irrigation, it usually carries with it some amount of various dissolved salts and anaerobic organisms which are carried to the water irrigation intake by circulation within the pond. The subsequent deposition of these salts and microorganisms is of course detrimental to the soil and vegetation.
In my related patent application referred to above, I described and claimed a system whereby such reservoirs could be continually cleaned of salts and harmful bacteria (such as anaerobes) and maintained with various beneficial microorganisms, such that the irrigation water being drawn from them would be or approach optimum for the irrigation of the soil and vegetation.
In many cases, however, parks and golf courses do not have such irrigation ponds or lakes, particularly in arid regions where the evaporation rate results in excessive water loss and makeup requirements. In some areas, such as the regions of California and the Southwest which have experienced drought conditions for the past several years, many municipalities have restricted or prohibited water make-up to open ponds because of the high loss rates. Consequently, it has become necessary to develop closed systems where water loss is minimized. Not only does a closed system prevent exposure of the water to the ambient air until it is actually applied to the vegetation, but unlike an open pond, which is exposed at all hours, a closed system can be operated only at the times of minimum evaporation, which is usually in the early morning hours. Further, closed systems have the advantage that they are free of contamination by unwanted microorganisms which could be deposited in an open pond by wind, rain, animals or other means. Consequently, it would be of advantage to have a closed system which retains all of the benefits of my previously described open system but which avoids the problems of open systems which I have just mentioned.